Study On Advanced Treatment Technology Of Low-Concentration Refractory Chemical Wastewater

Chemical wastewater treatment is one of the difficulties and hot spots in water treatment.With the further improvement of discharge standard,the advanced treatment technology of low concentration and difficult degradation chemical wastewater needs further research and development.In this study,the advanced treatment technology of chemical wastewater was studied.In the research process,ceramsite,steel shaving,granular carbon nitride,activated carbon loaded iron,iron carbon ball and other catalysts were selected to carry out the ozone catalytic oxidation experiment.With ozone alone oxidation as a control,the effects of catalyst type,ozone dosage,initial pH of wastewater and other factors on the removal of cod were studied.By using headspace solid-phase microextraction GC-MS,the relative changes of the types and proportions of organic compounds in wastewater before and after the process of iron carbon sphere catalytic ozonation were analyzed.Finally,a combined process of Fe-C-O catalytic oxidation+anaerobic activated coke biofilter+aerobic activated coke biofilter was formed to treat the COD and nitrogen-containing substances in the wastewater.Through the research,the conclusion is as follows:1.In the study of ozonation of wastewater,adding catalyst for ozonation is better than ozonation alone.Through the selection of catalyst,in the ozonation of wastewater,the catalytic effect of iron carbon sphere catalyst is better than that of ceramsite,steel shaving,granular carbon nitride and other catalysts selected in the experiment2.Using iron carbon ball as catalyst for ozone catalytic oxidation,this kind of low concentration chemical wastewater COD has obvious removal effect.When the initial pH of wastewater is 8,the ozone addition rate is 3 mg/(L·min)and the reaction time is 1 h,COD decreases from 186 mg/L to 117 mg/L,the removal rate is 37.1%,and B/C increases from 0.07 to 0.33.3.The biodegradability of the wastewater is improved obviously after the treatment of ozone catalytic oxidation.The removal efficiency of COD is better under the condition of 4H residence time than that of conventional plastic packing.The removal efficiency of COD is 39%and 35%respectively.At the same time,a small amount of ammonia nitrogen in wastewater can be effectively converted into nitrate nitrogen.When the anaerobic biofilm process is used to treat the effluent of ozone catalytic oxidation,the different membrane carriers have a small impact on the removal of COD and nitrate nitrogen;under the same residence time,plus 60?70mg/L carbon source,the removal rate of COD and nitrate nitrogen of the activated coke packing is higher than that of the conventional plastic packing anaerobic biofilm process.4.As far as the low concentration chemical wastewater is concerned,the combined process of ozone catalytic oxidation+anaerobic activated coke biofilter+aerobic activated coke biofilter is adopted.The COD of industrial wastewater is reduced from 181mg/L to 73mg/L,the ammonia nitrogen is reduced from 4.1mg/l to 0.2mg/l,the nitrate nitrogen is reduced from 20.8mg/l to 3.7mg/l,and the nitrite nitrogen is basically undetectable.The water quality of the effluent meets the primary discharge standard of the centralized industrial sewage treatment plant specified in the discharge standard of main water pollutants in the chemical industry(DB32/939-2006).5.In view of the low concentration and refractory chemical wastewater,ozone catalytic oxidation is the key technology.The process of ozone catalytic oxidation with iron carbon spheres as catalyst mainly uses hydroxyl radicals produced in the process of ozone catalytic oxidation to oxidize and degrade COD in wastewater.Hydroxyl radicals act on functional groups such as C-O bond of organic compounds,and then lead to chain reaction similar to alkane halogenation reaction,which makes organic compounds split and promotes the oxidation and decomposition of organic compounds.